The invention relates to an arrangement for coaxially securing an input component of a clutch, in particular of a friction clutch, to an output end of a crankshaft rotatable around an axis of rotation in an internal combustion engine of a motor vehicle.
Conventional friction clutches in motor vehicles generally include a single- or twin-part flywheel, onto which a pressure plate unit is detachably screwed. The pressure plate unit includes an axially movable contact plate, which is arranged to be rotationally fixed, but axially movable on a clutch housing screwed to the flywheel and is biased towards the flywheel by a pressure spring, usually a diaphragm spring. The contact plate and the flywheel form friction surfaces for a clutch disc arranged between them, the hub of which is supported to be rotationally fixed, but axially movable on an input shaft of a gear arranged downstream of it in the drive section of the motor vehicle. The flywheel is, moreover, screwed onto an end flange of the crankshaft of the internal combustion engine by means of a plurality of screws arranged around the axis of rotation of the crankshaft.
Viewed in axial direction, the clutch disc and the diaphragm spring in conventional friction clutches cover the screws securing the flywheel to the end flange of the crankshaft. Consequently, when assembling a friction clutch the flywheel must first be screwed onto the end flange, before the clutch disc can be put in place and the pressure plate unit can be screwed onto the flywheel. This assembly procedure is not only time-consuming, but also has the disadvantage that the friction clutch cannot be checked prior to assembly overall, that is including the clutch disc and the flywheel, to determine whether assembly regulations have been complied with.
From DE-A 41 17 571 it is known to arrange holes in both the clutch disc and the diaphragm spring, which are axially flush with the screws provided for securing the flywheel to the end flange of the crankshaft. In this way, the pressure plate unit can be assembled together with the clutch disc and the flywheel to form one structural unit, hereafter also referred to as a modular clutch, prior to installation on the crankshaft. The fastening screws may be tightened through the holes in the clutch disc and the diaphragm spring into the end flange of the crankshaft.
It is known from DE-A 33 15 232 to screw a friction clutch comprising flywheel, pressure plate unit and clutch disc, whereby the clutch housing borders the flywheel, i.e. is not detachably connected thereto, to the output end of the crankshaft by means of a central screw. The output end of the crankshaft contains a centric front opening provided with an internal thread, into which the central screw is screwed. The central screw has a radially projecting flange, which clamps the flywheel against the axial face of the output end of the crankshaft. The torque, which may be transmitted via the radial flange of the central screw, is however comparatively low, since only restricted fastening torques of the central screw may be achieved.
It is known from DE-A 40 13 298, for securing the flywheel of a friction clutch, to provide the axially facing surfaces of an end flange of the crankshaft and the flywheel with a radial gear tooth system (Hirth serration), and to axially fix the flywheel to the output end of the crankshaft by means of a central screw. The central screw is provided with centric key faces to accommodate a screw attachment tool.
It is known from the book .Die Motoren der Personenkraftwagen. (Automobile Engines), by K. Wiecking and R. Gebauer, Verlag Chr. Belser, Stuttgart, 1952, page 314, FIG. 341, to secure the flywheel of a conventional friction clutch to the output end of the crankshaft of an internal combustion engine by means of a cone press-fit joint. The output end bears an external cone tapering towards the clutch disc, on which the flywheel is mounted by an internal cone of its hub. The output end of the crankshaft ends in a screw journal, onto which a nut locking the flywheel is screwed.
Finally, it is known from the German Gebrauchsmuster 90 16 961 to provide a clamping joint between a shaft rotating around an axis of rotation and the hub of a component concentric to the axis of rotation. Conical elements are distributed over the periphery of the hub in conical recesses, and may be tightened in axial direction into the corresponding recesses by means of screws. The conical elements cause radial deformation of the hub and thus generate clamping forces acting on the shaft.